Antiarrhythmics - Class I

Question 1

Antiarrhythmics - Class I

Drug Names

Answer 1

• Ia: Disopyramide, procainamide, quinidine
• Ib: lidocaine*, mexiletine
• Ic: flecainide, propafenone

Question 2

Antiarrhythmics - Class I

Actions

Answer 2

Blocks sodium channels during AP (phase 0)

Decreases polarization

Decreases automacy of ventricular cells

Increases ventricular fibrillation threshhold

Question 3

What phase does class I effect?

Answer 3

phase 0

Question 4

Antiarrhythmics - Class I

Indications

Answer 4

Acute ventricular arrhythmias during surgery or MI

Question 5

Antiarrhythmics - Class I

Contraindications and cautions

Answer 5

CI: allergy, bradycardia, heart block, CHF, hypotension, shock, electrolyte disturbance

Cautions: renal/hepatic impairment, pregnancy

Question 6

Antiarrhythmics - Class I

Adverse Effects

Answer 6

• CNS: dizzy, fatigue, slurred speech
• GI: N/V
• CV: arrhythmias**
• Resp depression
• Rash
• Hair loss
• Bone marrow suppression

Question 7

Antiarrhythmics - Class I

Drug-Drug Interactions

Answer 7

Quinidine and digoxin
BC
beta blockers

Question 8

Antiarrhythmics - Class I

Drug-Food Interactions

Answer 8

Foods that alkalize urine - citrus, veggies, milk

Grapefruit juice